Monday, March 15, 2010

Dustbin fairings and motorcycle racing: Where’s the future?

Back in the 1950s, manufacturers like Gilera, Moto Guzzi and Norton were using all-enveloping 'dustbin' fairings on their racebikes. These fairings were finally banned in 1957 by the FIM...

Back in 1957, the FIM banned ‘dustbin fairings’ from motorcycle racing. Back then, various manufacturers used these kind of fairings – essentially an all-enveloping, streamlined shell that must have helped aerodynamics – on their bikes, with a fair bit of success. However, bikes with these fairings became very unstable in crosswinds and in some cases the fairings also interfered with lock-to-lock steering movement.

Over the last few decades, all-enveloping bodywork has occasionally been used on a few prototype motorcycles by some inventors / innovators, usually in the quest for improved fuel efficiency or straight-line top speed. Mainstream manufacturers have, however, steered clear of the erstwhile ‘dustbin fairing,’ which hasn’t been seen on racing bikes or production machines for as long as we can remember.

Recently, with the increasing popularity of electric bikes, battery-powered racebikes and the TTXGP series, there has been some talk of reviving the dustbin fairing on e-racing bikes, since it would, potentially, help with aerodynamics and boost top speeds by a big margin. The TTXGP rules do not prohibit the use of such fairings on battery-powered racebikes, though for many, this remains a controversial subject.

Michael Czysz, the man behind MotoCzysz, recently wrote a detailed piece on his own blog, outlining the possible dangers of reviving the dustbin fairing. ‘What made the dustbin fairing dangerous for 50s-era racing motorcycles, makes it suicidal for 2010 era racing motorcycles. Take a modern motorcycle and add a large side area or fairing to it, and it will be subjected to forces beyond the rider's control,’ says Czysz.

‘Stretch that fairing fore and aft the wheels and you have now increased the leverage of that force and effect. Add additional height and now the fairing is subject to even higher wind speeds that have an even greater lever to lean and pull the motorcycle. More frightening, the rider can only overcome the unwanted change in direction by turning the motorcycle towards its new trajectory as to counter the lean initiated by the wind. This is a very counter intuitive maneouver that takes additional time and real estate most racers do not have,’ he adds.

The Britten V1000, with its minimalist bodywork, and the Suzuki Hayabusa, with its streamlined, almost all-enveloping fairing prove that there's more than one way of going very fast...

Quoting various real world examples, Czysz says that motorcycles with all-enveloping bodywork may not remain stable even in a straight line, let alone corners. ‘As efficiency is such a component to electric racing, it is easy to see why someone may think this [the use of dustbin fairings] is a good idea, but I am certain this same person has no modern day racing experience,’ he says.

All of this quite interesting for anyone who loves fast motorcycles. Looking back over the last two decades, we can see that there are at least two schools of thought on motorcycle aerodynamics. One is what you see with bikes like the Suzuki Hayabusa and the Kawasaki ZZR1400 – big, bulbous fairings and the very evident use of streamlining. The Hayabusa, especially, uses the closest modern day equivalent of a dustbin fairing and, hey, it also happens to be the fastest production motorcycle in the world! However, there have also been bikes like the Britten V1000 and various Buell machines, which went with minimal bodywork and which were not only very fast, but also handled extremely well.

So, really, what are the chances of the old dustbin fairing making a comeback to top-flight motorcycle racing? To get some answers, we spoke to Greg Taylor, who has a degree in automotive engineering design and who’s spent two decades in the automotive and motorcycle industries. Among other things, Greg has also worked on Lotus race cars and with Triumph, as a senior engineer, where he was responsible for engineering the TT600’s bodywork, which involved testing the motorcycle in the MIRA full-scale wind tunnel.

I think Michael Czysz is right not to elect to race a ‘dustbin’ type fairing. This is essentially a 1950s design that has had no development in the last 50 years. The dustbin fairing was proven to be a flawed design, so I don't understand why it is being suggested as an answer to streamlining now,’ says Greg. ‘However, I think the phrase ‘dustbin fairing’ is being used as a catch-all term for streamlining and aerodynamic improvements, and its use is confusing what is really trying to be achieved – that is to improve the overall efficiency of the motorcycle,’ he adds.

The Peraves MonoTracer (above) and the Ecosse ES1 (below, left) are just two machines that have, in their own way, experimented with full, all-enveloping bodywork in recent years...

‘Don't forget that the original dustbin fairing was a worthy attempt at trying to improve top speeds. The teams using these fairings were trying new technology to gain a competitive advantage, which is what racing is all about,’ says Greg. ‘Do I think dustbin fairings will make a comeback? Hopefully, not in their original form. However, the philosophy behind the dustbin fairing is making a comeback. The motorcycle industry is being forced to produce less emissions, and owners are seeking more fuel efficient machines. The improvement in efficiencies required cannot be achieved through engine development only. Aerodynamics will play a significant part in helping motorcycles to burn less fuel for a given speed,’ he adds.

‘Hybrid and electric motorcycles require efficient aerodynamics far more than their petrol burning cousins. The energy content of batteries is tiny compared to petrol, so an all-electric motorcycle will have to cut through the air very efficiently to travel a credible distance,’ explains Greg.

‘Race series should be encouraging the design of bodywork that reduces aerodynamic drag. Racing will provide rapid development of aerodynamic features that reduce drag, without affecting stability and handling. Modern sports cars feature sophisticated aerodynamic features and devices that provide downforce, with little affect on drag. These aerodynamic features were developed over many years in racing. Motorcycle racing should be encouraging similar aerodynamic developments relevant to our sport, which can then benefit the bikes we buy to ride. I believe electric motorcycle racing will provide the environment for rapid development of aerodynamics. These developments will, no doubt, benefit petrol powered motorcycles, also,’ he adds.

So there you are – the dustbin fairing probably isn’t coming back, though motorcycles – especially high-performance streetbikes, electric bikes and electric/hybrid racing bikes – in the near future may make more effective use of streamlining and aerodynamics. If that means a 400km/h Hayabusa, we’re all for streamlining and aerodynamics…!

12 comments:

Rarely moved to comment, the abject baloney spouted off on the subject of motorcycle aerodynamics moves me as all the old myths are trotted out as if they were facts.

Lets compare the fifties with the Noughties in areas where aerodynamics have made an impact: The average fighter jet flew at subsonic speeds in the fifties and could sustain 6-7g. Todays fighter can maintain supersonic cruise without reheat, and thanks not only to aerodynamic refinement but also billions of dollars of research into the ergonomics can allow the pilot to sustain 9-11g. Understanding of a single concept permitted this - area rule

Next: Downforce = drag. That's what it is, a force acting in a non-linear motion relative to the direction of travel. It cannot be anything else.

The Ecomobile, with its huge overhangs, has proved over more than 25 YEARS that it is LESS susceptible to crosswinds than conventional `bicycles-with-engines`. The fleet has, over millions of kilometers, proved beyond all doubt that design for aerodynamic purposes MUST include `dustbin` concepts.

I can go into this much farther, but Czysz and Taylor should restrict themselves to what they KNOW, not what they think they know. I've been involved in aerodynamics for aircraft, ships and motor vehicles for years.

Like Greg said, streamlining is important and will work, dustbin fairings might not. The two are not the same thing. And as for Czysz, he might be brilliant with electrics and electronics but maybe he doesn't know jack about aerodynamics?

What did or did not work on racebikes in the 1950s can't possibly have any bearing with what'll work now. Tyres, suspension, chassis, electronics - these things are likely to have changed everything. I don't know or give a rat's about "dustbin fairings" and neither would most pro racers whom I know and work with. We just want to go faster. If "all enveloping" bodywork let's us do that, hey, bring it on!

Dunno about Greg but isn't this Czysz the same bloke whose 990cc MotoGP bike never took off, then his electric bike didn't get off the starting grid at the TTXGP last year? And he's talking about motorcycle aerodynamics and dustbin fairings?? Gimme a break! :-D

The only reason his 990cc bike never took off is because they moved to 800cc? Thought that was pretty obvious. Additionally, technical faults are exactly that, and occur in every racing sport on the planet, hardly a reflection of one man's abilities. Personally, I'm going to trust the man who HAS BUILT 2 WORKING MOTORCYCLE'S. A fact I think many here are forgetting.

The banning of dustbin fairings half a century ago was a kneejerk reaction to the sudden rash of fatalities on those bikes equipped with them. But was it caused directly by aerodynamics? There is every chance the cause was the sudden increase in speed catching out the tyre technology of the era. This happened again in the 70's on the fast banked circuits of the US.

Bearing in mind we now have the ability to both computer model and test the effects of fairings in cross winds it is high time they are considered again.

Bike drag coefficients are vastly higher than todays cars, making even medium sized bikes consume more fuel than small cars. This makes bikes economically irrelevant. Time to get into the 21st century.

My money says dustbins can be made to work, by somebody who has the will to try. And I've damn near been blown off bridges and highways by sidewinds on small unfaired bikes so understand the concerns. But the above experts quote no data or modern experiments involving dustbins, and I am disinclined to believe their self-assured pronouncements, which seem pulled out of their oversized hats. Many faired bikes have side surfaces almost as great as an old dustbin, and unfaired bikes are hardly tested to optimize flow-through from the side. I do not believe this issue has been addressed scientifically let alone resolved. Motorcycling MUST increase its fuel efficiency in order to justify its long-term existence, and aerodynamics are the problem. Otherwise bikes, which not long ago were practical transportation, will become in view of public policy wasteful, undesireable toys.

Simon as a simple magic marker smith always eager to learn I'd love to hear more about your credentials and read your thesis on motorcycle aerodynamics. Any specific examples of working on motorcycles (motorcycles are not aeroplanes or motorcars and behave very differently) where you have applied, tested and validated your extensive knowledge would be very welcome and really help to back up your response.

Tony Foale's article here is very interesting and touches on the problems of both streamlining and lateral lift. http://www.tonyfoale.com/Articles/Aerodynamics/AERO.htm

You could also join our little motorcycle r&d forum on linkedin where you can discuss motorcycle design issues. I wait with excitement to hear your response.

Well!! You have done an outstanding job by posting such remarkable information about motorcycle fairings. This is really interesting information for me, at that time mostly people prefer this type of customized bikes for racing. It was really looks cool… Keep sharing such more info.

I'm sure a few of the motorcycles,had some adverse handling problems when they encountered crosswinds back in the day.But if I had to guess what was really going on back then,I think the bikes were going too fast for the technology of the time.The brakes,suspension's,frames etc just couldn't handle the increased speeds afforded by the aerodynamic add ons.Streamlining today would be a different story, not only could we eliminate most of the adverse lateral movement,encountered in strong crosswinds,the motorcycles would be safer,faster, all while using a lot less energy.